Video signal format

Abstract

A video signal that is representative of a wide scene comprises signal elements corresponding to a plurality of horizontal line intervals of a raster. A luminance component and two chrominance components are included in each horizontal line interval, in time-compressed sequential relationship. The video signal also incorporates information representative of a number in the range from zero to the difference between the aspect ratio of the wide scene and the aspect ratio of a scene represented by a conventional video signal format. This information determines the portion of the wide scene that is represented by a video signal of the conventional format derived from the video signal representative of the wide scene.

We claim: 
     
       1. A method of generating from an input video signal of a first format an output video signal that can be converted to a second format, a signal of said first format (a) being representative of a scene having a first aspect ratio,   (b) comprising signal elements corresponding to a plurality of horizontal line intervals of a raster, said lines and said raster occurring at respective predetermined rates, and   (c) including in each horizontal line interval, in time-coincident relationship, information relating to the amplitude of three primary color components of the scene, and a signal of said second format     (a) being representative of a scene having a second aspect ratio, smaller than said first aspect ratio,   (b) comprising signal elements corresponding to a plurality of horizontal line intervals of a raster, said lines and said raster of the second signal format occurring at respective predetermined rates, and   (c) including in each horizontal line interval a luminance component and two chrominance components in time-coincident relationship, said method comprising forming a luminance component and two chrominance components from the signal elements of the input video signal, time-compressing the luminance and chrominance components and time-division multiplexing the luminance and chrominance components into respective time slots during a succession of intervals occurring at a predetermined rate, and also incorporating within the output video signal information representative of a number in the range from zero to the difference between said aspect ratios.     
     
     
       2. A method according to claim 1, wherein the lines and raster of the second signal format occur at the same rates as the lines and raster of the first signal format, and the intervals containing said time slots occur at the same rate as the lines of the first signal format. 
     
     
       3. A method according to claim 1, wherein the raster of the second format occurs at the same rate as the raster of the first signal format, and the number of lines in the raster of the second format is equal to the number of lines in the raster of the first signal format divided by a positive integer. 
     
     
       4. A method according to claim 3, wherein said positive integer is equal to one and the intervals containing said time slots occur at the same rate as the lines of the first signal format. 
     
     
       5. A method according to claim 4, wherein the step of time-compressing the luminance and chrominance components is accomplished by digitizing each component and writing it into memory under control of a clock at a first frequency, and reading each component out of memory under control of a clock at a second, higher frequency. 
     
     
       6. A method according to claim 5, wherein the first and second frequencies are integral submultiples of 2,730 times the frequency at which the horizontal lines of the first signal format occur. 
     
     
       7. A method according to claim 5, wherein the first and second frequencies are integral submultiples of 2,880 times the frequency at which the horizontal lines of the first signal format occur. 
     
     
       8. A method according to claim 5, wherein the step of time-division multiplexing is accomplished by reading the luminance and chrominance components out of memory during different respective time slots. 
     
     
       9. A method according to claim 4, wherein the aggregate duration of the three time slots into which the luminance and chrominance components are multiplexed during each said interval is less than the period corresponding to the rate at which the lines of the first signal format occur, and said information is incorporated within the output video signal in a time slot that occurs at the same rate as the lines of the first signal format. 
     
     
       10. A method according to claim 4, wherein the steps of time-compressing the luminance and chrominance components and time-division multiplexing the luminance and chrominance components is accomplished by digitizing the luminance component under control of a clock at a first frequency, digitizing the chrominance components under control of a clock at a second, lower frequency, writing the digitized components into memory under control of clocks at said first and second frequencies respectively, and reading the digitized components out of memory during different respective time slots under control of a clock at a third frequency that is higher than the first frequency. 
     
     
       11. A method according to claim 4, wherein the step of time-compressing the luminance and chrominance components and time-division multiplexing the luminance and chrominance components is accomplished by digitizing the luminance component under control of a clock at a first frequency, digitizing the chrominance components under control of respective clocks at second and third lower frequencies, writing the digitized components into memory under control of clocks at said first, second and third frequencies respectively, and reading the digitized components out of memory during different respective time slots under control of a clock at a fourth frequency that is higher than the first frequency. 
     
     
       12. A method according to claim 1, further comprising converting said output video signal to a signal of said second format by time-expanding the luminance and chrominance components of the output video signal and bringing said components into time-coincident relationship, and utilizing said information to define, within the scene represented by the output video signal, a selected portion having said second aspect ratio, and excluding from the signal of said second format portions of the luminance and chrominance components that correspond to areas of the scene represented by the output video signal that are outside said selected portion. 
     
     
       13. A method according to claim 12, wherein the lines and raster of the second signal format occur at the same rates as the lines and raster of the first signal format, and the intervals containing said time slots occur at the same rate as the lines of the first signal format. 
     
     
       14. A method according to claim 13, wherein the step of time-expanding the luminance and chrominance components is accomplished by digitizing each component and writing it into memory under control of a clock at a first frequency, and reading each component out of memory under control of a clock at a second, lower frequency. 
     
     
       15. A method according to claim 14, wherein the first and second frequencies are integral submultiples of 2,730 times the frequency at which the horizontal lines of the first signal format occur. 
     
     
       16. A method according to claim 14, wherein the first and second frequencies are integral submultiples of 2,880 times the frequency at which the horizontal lines of the first signal format occur. 
     
     
       17. A method according to claim 13, wherein the step of bringing the components into timecoincident relationship is accomplished by reading the luminance and chrominance components out of memory simultaneously. 
     
     
       18. A method according to claim 13, wherein the step of time-expanding the luminance and chrominance components and bringing the luminance and chrominance components into time-coincident relationship is accomplished by digitizing each component and writing it into memory under control of a clock at a first frequency, and simultaneously reading the luminance component out of memory under control of a clock at a second, intermediate frequency and reading the chrominance components out of memory under control of a clock at a third, lower frequency. 
     
     
       19. A method according to claim 13, wherein the step of time-expanding the luminance and chrominance components and bringing the luminance and chrominance components into time-coincident relationship is accomplished by digitizing each component and writing it into memory under control of a clock at a first frequency, and simultaneously reading the luminance component out of memory under control of a clock at a second, intermediate frequency and reading the two chrominance components out of memory under control of respective clocks at third and fourth lower frequencies. 
     
     
       20. A method of converting an input video signal of a first format into an output video signal of a second format, a signal of said first format (a) being representative of a scene having a first aspect ratio,   (b) comprising signal elements corresponding to a plurality of horizontal line intervals of a raster, said lines and said raster occurring at respective predetermined rates,   (c) including in each horizontal line interval, in time-compressed sequential relationship, a luminance component and two chrominance components, and   (d) incorporating information representative of a number in the range from zero to the difference between said first aspect ratio and a second, smaller aspect ratio, and a signal of said second format     (a) being representative of a scene having said second aspect ratio,   (b) comprising signal elements corresponding to a plurality of horizontal line intervals of a raster, said lines and said raster of the second signal format occurring at respective predetermined rates, and   (c) including in each horizontal line interval a luminance component and two chrominance components in time-coincident relationship, said method comprising time-expanding the luminance and chrominance components of the input video signal and bringing said components into time-coincident relationship, utilizing said information to define, within the scene represented by the input video signal, a selected portion having said second aspect ratio, and excluding from the output video signal portions of the luminance and chrominance components that correspond to areas of the scene represented by the input video signal that are outside said selected portion.     
     
     
       21. A method according to claim 20, wherein the lines and raster of the first signal format occur at the same rates as the lines and raster of the second signal format. 
     
     
       22. A method according to claim 20, wherein the raster of the second signal format occurs at the same rate as the raster of the first signal format, and the number of lines in the raster of the second format is equal to the number of lines in the raster of the first signal format divided by a positive integer. 
     
     
       23. A method according to claim 22, wherein said positive integer is equal to one. 
     
     
       24. A method according to claim 23, wherein the step of time expanding the luminance and chrominance components of the input video signal is accomplished by digitizing each component and writing it into memory under control of a clock at a first frequency, and reading each component out of memory under control of a clock at a second, higher frequency. 
     
     
       25. A method according to claim 24, wherein the first and second frequencies are integral submultiples of 2,730 times the frequency at which the horizontal lines of the first signal format occur. 
     
     
       26. A method according to claim 24, wherein the first and second frequencies are integral submultiples of 2,880 times the frequency at which the horizontal lines of the first signal format occur. 
     
     
       27. A method according to claim 24, wherein the step of bringing the components into time-coincident relationship is accomplished by reading the luminance and chrominance components out of memory simultaneously. 
     
     
       28. Apparatus for generating, from an input video signal of a first format, an output video signal that can be converted to a second format, a signal of said first format (a) being representative of a scene having a first aspect ratio,   (b) comprising signal elements corresponding to a plurality of horizontal line intervals of a raster, said lines and said raster occurring at respective predetermined rates, and   (c) including in each horizontal line interval, in time-coincident relationship, information relating to the amplitude of three primary color components of the scene, and a signal of said second format     (a) being representative of a scene having a second aspect ratio, smaller than said first aspect ratio,   (b) comprising signal elements corresponding to a plurality of horizontal line intervals of a raster, said lines and said raster of the second signal format occurring at respective predetermined rates, and   (c) including in each horizontal line interval a luminance component and two chrominance components in time-coincident relationship, said apparatus comprising means for forming a luminance component and two chrominance components from the signal elements of the input video signal, means for time-compressing the luminance and chrominance components and time-division multiplexing the luminance and chrominance components respective time slots during a succession of intervals occurring at a predetermined rate, and means for incorporating within the output video signal information representative of a number in the range from zero to the difference between said aspect ratios.     
     
     
       29. Apparatus according to claim 28, wherein the raster of the second signal format occurs at the same rate as the raster of the first signal format, and the number of lines in the raster of the second format is equal to the number of lines in the raster of the first signal format, and the means for time-compressing and time-division multiplexing the luminance and chrominance components comprise means for multiplexing said components into respective time slots during intervals that occur at the same rate as the lines of the first and second signal formats. 
     
     
       30. Apparatus according to claim 29, wherein the means for time-compressing the luminance and chrominance components and time-division multiplexing the luminance and chrominance components comprise means for digitizing each component and writing it into memory under control of a clock at a first frequency, and reading each component out of memory under control of a clock at a second, higher frequency. 
     
     
       31. Apparatus according to claim 30, comprising a master clock generator for generating a master clock at a frequency 2,730 times the frequency at which the horizontal lines of the first signal format occur, and frequency divider means for generating the clocks at the first and second frequencies by dividing the frequency of the master clock by at least first and second integers. 
     
     
       32. Apparatus according to claim 30, comprising a master clock generator for generating a master clock at a frequency 2,880 times the frequency at which the horizontal lines of the first signal format occur, and frequency divider means for generating the clocks at the first and second frequencies by dividing the frequency of the master clock by at least first and second integers. 
     
     
       33. Apparatus according to claim 30, wherein the means for time-compressing the luminance and chrominance components and time-division multiplexing the luminance and chrominance components comprise means for reading the digitized components out of memory during different respective time slots. 
     
     
       34. Apparatus according to claim 29, wherein the aggregate duration of the three time slots into which the luminance and chrominance components are multiplexed during each said interval is less than the period corresponding to the rate at which the lines of the first signal format occur, and the means for incorporation said information into the output video signal comprise means for time-division multiplexing said information into a fourth time mslot that occurs at the same rate as the lines of the first signal format. 
     
     
       35. Apparatus for converting an input video signal of a first format into an output video signal of a second format, a signal of said first format (a) being representative of a scene having a first aspect ratio,   (b) comprising signal elements corresponding to a plurality of horizontal line intervals of a raster, said lines and said raster occurring at respective predetermined rates, and   (c) including in each horizontal line interval, in time-compressed sequential relationship, a luminance component and two chrominance components, and   (d) incorporating information representative of a number in the range from zero to the difference between said first aspect ratio and a second, smaller aspect ratio, and a signal of said second format     (a) being representative of a scene having said second aspect ratio,   (b) comprising signal elements corresponding to a plurality of horizontal line intervals of a raster, said lines and said raster of the second signal format occurring at respective predetermined rates, and   (c) including in each horizontal line interval a luminance component and two chrominance components in time-coincident relationship, said apparatus comprising means for timeexpanding the luminance and chrominance components of the input video signal and bringing said components into time-coincident relationship, and means for utilizing said information to define, within the scene represented by the input video signal, a selected portion having said second aspect ratio and to exclude from the output video signal portions of the luminance and chrominance components that correspond to areas of the scene represented by the input video signal that are outside said selected portion.     
     
     
       36. Apparatus according to claim 35, wherein the raster of the second signal format occurs at the same rate as the raster of the first signal format, and the number of lines in the raster of the second format is equal to the number of lines in the raster of the first signal format, and the means for time-compressing and time-division multiplexing the luminance and chrominance components comprise means for multiplexing said components into respective time slots during intervals that occur at the same rate as the lines of the first and second signal formats. 
     
     
       37. Apparatus according to claim 36, wherein the means for time-expanding the luminance and chrominance components of the input video signal and bringing said components into time-coincident relationship comprise means for digitizing each component and writing it into memory under control of a clock at a first frequency, and reading each component out of memory under control of a clock at a second, lower frequency. 
     
     
       38. Apparatus according to claim 37, comprising a master clock generator for generating a master clock at a frequency 2,730 times the frequency at which the horizontal lines of the first signal format occur, and frequency divider means for generating the clocks at the first and second frequencies by dividing the frequency of the master clock by at least first and second integers. 
     
     
       39. Apparatus according to claim 37, comprising a master clock generator for generating a master clock at a frequency 2,880 times the frequency at which the horizontal lines of the first signal format occur, and frequency divider means for generating the clocks at the first and second frequencies by dividing the frequency of the master clock by at least first and second integers. 
     
     
       40. Apparatus according to claim 37, wherein the means for bringing the luminance and chrominance components into time-coincident relationship comprise means for reading the digitized components out of memory simultaneously.